The coalescence mechanism, in which light nuclei are usually assumed to be produced by the coalescence of the jacent nucleons in the phase space, possesses its unique characteristics.
Plenty of current experimental observations at high RHIC and LHC energies favor the nucleon coalescence [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}.
Recently the STAR collaboration has extended the beam energy scan program to lower collision energy and published the data of both hadrons and light nuclei in Au-Au collisions at \(\sqrt{s_{NN}}=3\)  GeV erewhile [8]}, [9]}, [10]}, [11]}.
These new data show very different properties compared to those at high RHIC and LHC energies, such as the disappearance of partonic collectivity [8]} and dominant baryonic interactions [9]}.
At this low collision energy besides nucleons, light nuclei in particular of light \(d\) , \(t\)  and \(^3\) He have been more abundantly created [11]} compared to higher collision energies [15]}.
It is easier in physics for these light nuclei to capture nucleons or other light nuclei to form heavier composite objects.
In fact clear depletions below unity of proton\(-d\)  and \(d-d\)  correlation functions measured at such low collision energy indicate the strong final state interaction and further support the possible coalescence of light nuclei and/or nucleons [16]}.
How much space is there on earth for other particle coalescence except nucleons, e.g., composite particles of less mass numbers coalescing into light nuclei of larger mass numbers or composite particles capturing nucleons to recombine into heavier light nuclei?
